1992 F250 Failed Emissions - high NOX
Thanks man. I read up on egr tests, and I'll do those.
One more question:
There are 3 valves of some kind mounted to a bracket on top of the engine. They are plumbed into the egr stuff. What are these, and can they go bad? After I turn off the engine, one of 'em makes a buzzing noise for a few seconds...